#include<bits/stdc++.h>
using namespace std;
int main()
{
	double x[4],y[4],d[4];
	int i;
	for(i=1;i<=3;i++)
	cin>>x[i]>>y[i];
	d[1]=sqrt((x[1]-x[2])*(x[1]-x[2])+(y[1]-y[2])*(y[1]-y[2]));
	d[2]=sqrt((x[2]-x[3])*(x[2]-x[3])+(y[2]-y[3])*(y[2]-y[3]));
	d[3]=sqrt((x[1]-x[3])*(x[1]-x[3])+(y[1]-y[3])*(y[1]-y[3]));
	printf("%.2f",d[1]+d[2]+d[3]);
    return 0;
}
